The UK has temporarily withdrawn all staff from the Yemen embassy "due to increased security concerns".

The development came after the US State Department urged citizens and non-emergency government staff to leave for the same reason.

Intercepted conversations between two senior al-Qaida figures, including top leader Ayman al-Zawahiri, prompted the closure of 20 US embassies and consulates in North Africa and the Middle East. The measure was "out of an abundance of caution" the US said.

The New York Times quoted an American official briefed on the intelligence report who said: "This was significant because it was the big guys talking, and talking about very specific timing for an attack or attacks."

The other terrorist figure is Nasir al-Wuhayshi, head of al-Qaida in the Arabian Peninsula (AQAP), a significant player in the Islamist organisation.

"Due to increased security concerns, all staff in the British Embassy have been temporarily withdrawn and the Embassy will remain closed until staff are able to return," the Foreign Office said on its website.

The withdrawal came just hours after a suspected US drone killed four suspected al-Qaida members in Yemen's eastern province.

Unnamed officials told Reuters that the drone fired a missile and hit a car carrying the four men in the al-Arqeen district of Marib province, setting it on fire and killing all of them.

Tuesday's drone strike is the fourth of its kind since 28 July. The raids have killed 17 suspects in one week.